The present invention relates a device and method for treatment of cardiac disease and related cardiac complications. In particular, the present invention relates to a device for treating cardiac disease that includes a jacket that is adapted to be secured to the heart, and non-adherent material provided in association with the jacket.
Chronic or congestive heart disease is a progressive and debilitating illness. The disease is characterized by a progressive enlargement of the heart. Often, heart failure develops as a consequence of coronary artherosclerosis and myocardial infarction. After an infarction, the irreversibly injured myocardium is gradually replaced with fibrous scar tissue, since myocytes have limited ability to proliferate, and lost myocytes cannot regenerate. As myocytes are replaced with fibroblasts and collagen, changes in the mechanics of the heart lead to progressive onset of congestive heart failure.
As the heart enlarges, the heart is performing an increasing amount of work in order to pump blood with each heart beat. In time, the heart becomes so enlarged the heart cannot adequately supply blood. An afflicted patient is fatigued, unable to perform even simple exerting tasks and experiences pain and discomfort. Further, as the heart enlarges, the internal heart valves cannot adequately close. This impairs the function of the valves and further reduces the heart""s ability to supply blood.
Causes of congestive heart disease are not fully known. In certain instances, congestive heart disease may result from viral infections. In such cases, the heart may enlarge to such an extent that the adverse consequences of heart enlargement continue after the viral infection has passed and the disease continues its progressively debilitating course.
Patients suffering from congestive heart disease are commonly grouped into four classes (i.e., NYHA Classes I, II, III and IV). In the early stages (e.g., Classes I and II), drug therapy is the commonly proscribed treatment. Drug therapy treats the symptoms of the disease and may slow the progression of the disease. Importantly, there is no cure for congestive heart disease. Even with drug therapy, the disease will progress. Further, the drugs may have adverse side effects, particularly when they are administered through the bloodstream.
Presently, the only permanent treatment for congestive heart disease is heart transplant. To qualify, a patient must be in the later stage of the disease (e.g., Classes III and IV with Class IV patients given priority for transplant). Such patients are extremely sick individuals. Class III patients have marked physical activity limitations and Class IV patients are symptomatic even at rest.
Due to the absence of effective intermediate treatment between drug therapy and heart transplant, Class III and IV patients will have suffered terribly before qualifying for heart transplant. Further, after such suffering, the available treatment is unsatisfactory. Heart transplant procedures are very risky, extremely invasive and expensive and only shortly extend a patient""s life. For example, prior to transplant, a Class IV patient may have a life expectancy of 6 months to one-year. Heart transplant may improve the expectancy to about five years.
Unfortunately, not enough hearts are available for transplant to meet the needs of congestive heart disease patients. In the United States, in excess of 35,000 transplant candidates compete for only about 2,000 transplants per year. A transplant waiting list is about 8-12 months long on average and frequently a patient may have to wait about 1-2 years for a donor heart. While the availability of donor hearts has historically increased, the rate of increase is slowing dramatically. Even if the risks and expense of heart transplant could be tolerated, this treatment option is becoming increasingly unavailable. Further, many patient""s do not qualify for heart transplant for failure to meet any one of a number of qualifying criteria.
Congestive heart failure has an enormous societal impact. In the United States alone, about five million people suffer from the disease (Classes I through IV combined). Alarmingly, congestive heart failure is one of the most rapidly accelerating diseases (about 400,000 new patients in the United States each year). Economic costs of the disease have been estimated at $38 billion annually.
Not surprising, substantial effort has been made to find alternative treatments for congestive heart disease and related complications. One alternative treatment is described in commonly assigned U.S. Pat. No. 5,702,343 to Alferness dated Dec. 30, 1997 teaches a jacket to constrain cardiac expansion during diastole. The present invention pertains to improvements to the invention disclosed in the ""343 patent.
The present invention provides a device and method for treating cardiac disease and related cardiac complications. According to the invention, the device comprises a jacket that is adapted to be secured to the heart, and a non-adherent material in association with the jacket. Preferably, the non-adherent material prevents unwanted fibrosis or adhesion to the heart as a result of the presence of the jacket on the heart surface. The non-adherent material can be formed as an integral part of the jacket, or can be provided as a separate element of the overall device. Positioning of the non-adherent material can be controlled to reduce the risk of fibrosis or other adverse effects on the surface of the heart or surrounding organs. Preferably, the non-adherent material is located within or on the jacket such that it overlies areas of the heart surface containing major blood vessels, to facilitate access to those blood vessels, if the need should arise. The non-adherent material also facilitates removal of the jacket, if such removal becomes desirable or necessary. In one embodiment, the non-adherent material comprises a coating on the jacket. Alternatively, the non-adherent material comprises a separable element of the device and is provided in connection with the jacket.
In one embodiment, a device for treating cardiac disease comprises a jacket of flexible material that is secured to the heart and conforms to an external geometry of the heart, and a non-adherent material to prevent unwanted fibrosis on the surface of the heart. Preferably, the jacket is adapted to be adjusted on the heart to snugly conform to an external geometry of the heart and assume a maximum adjusted volume for the jacket to constrain expansion of the heart beyond the maximum adjusted volume during diastole and permit substantially unimpeded contraction of the heart during systole. In one aspect, the non-adherent material is adapted to cover only a specific area, or the entire surface area, of the heart.
In another embodiment, methods for treating cardiac disease and related cardiac complications are described, the method comprising surgically accessing the heart; applying a treatment device on the heart, the device comprising a jacket of flexible material that is secured to the heart and conforms to an external geometry of the heart, and a non-adherent material in association with the jacket; securing the treatment device to the heart; and surgically closing access to the heart while leaving the treatment device on the heart.